High-capacity boiler



Dec. 6, 1932. v w. H. ARMACOST ET AL 1,839,740

HIGH CAPACITY BOILER Filed Nov. 18, 1930 Wilbur H. Armaast and. Dag b rfW Rudorff Patented Dec. 6, 1932 UNITED STATES PATENT OFFICE W'ILBUB H. ABM-A0081 AN D DAGOIBEBT W. RUDORFF, OF NEW YORK, N. Y ASSIGNOBS TO THE SUPERHEATEB- COMPANY, OF NEW YORK, N. Y. i

HIGH-CAPACITY BOILER I Application filed November 18, 1930. Serial No. 496,375.

Our inventionrelates to boilers and aims to provide a boiler adapted to operate at high ratings without undue upkeep.

ited by the volume of the combustion chamher and that the gases undergoin combustion should not be chilled before t eir combustion has been completed, so that the ordi- -nary boiler surfaces have been placed much higher above the combustion zone than. was once the case. At the same time, boiler sizes have been largely increased. The effect of these tendencies has been to greatly increase the temperatures in the average boiler furnace and so to increase the upkeep ofthe refractories in the walls of the combustion chamber that water tubes have been very largely installed in order to shadethe refractories. It has been found that these. waterwalls, being so placed as to receive heat by direct radiation, generate steam at so high a rate per square foot that the amount of con vection heated absorbing surface per boiler horse-power may be greatly reduced.

The required rapidity of the thermosiphonic circulation of the boiler, however, depends largely upon the steam output so that the crass-section of the downcomer space of the boiler cannot be reduced in proportion to the total reduction in the convection heated surface without danger of retarding the circulation'at high outputs tua' point below that needed to prevent overheating of the tubes and thereby increasing the upkeep and depreciation of the boiler.

It is an object of the presentinvention to increase the efliciency of the downcomers of boilers.

As a further result of the use of water tubes on the walls of the combustion chamber, the floor space of the furnace in the average recent boiler installation is greater than the horizontal section of the convection heat: ing tubes of the boiler. As the convection heated tubes are ordinarily placed in vertical alinement with the combustion space, the space efliciency of the combination has suffered.

It is a further object of our invention to improve the space efficiency of boiler installations having combustion chambers provided'with water cooled walls.

In accordance with our invention, the

space efficiency of the boiler is improved by placing the entire superheater surface and also an additional heater,- either a steam reheater or a feedwater-heater, within the convection heated tubes.

The novel features of our invention will be pointed out in the appended claims. The invention itself, however, together with further objects and advantages, will best be understood from the following detailed description, in connection with the accompanying drawing, of an illustrative embodiment of our invention. In said drawing,

Fig. 1 is a vertical sectional view of a super heater reheater boiler installation;

' Fig. 2 is a fragmentary sectional plan view of the apparatus shown in Fig. 1, the roof being omitted for purposes of illustration.

In the boiler apparatus illustrated in the drawing, a combustion chamber 10 has a 12, 12 mounted in an up-pass 14 extending the full width of the boiler receiving gas from said chamber at its lower end and formed between abafile 16 and a front wall 18 of the boiler setting. Pass 14 has a tube-free space therein in which are superheater elements 15.

The tubes 12-12 connect at their lower ends into a water drum and at their upper endsto a steam and water drum 22. The walls of the chamberlO and of the pass 14, moreover, are lined with water tubes for protecting the refractories on the walls of the chamber 10, the wall 18 of the up-pass 14, and in the bafile 16. The water tubes on the front wall of the chamber lOare indicated at 24-. and connect into 'a header 26, header 26 being connected in turn to the steam and water drum 22 by a set of tubes 28 which run first inwardly from the header and thence upwardly along theconvection heated bank of generating tubes 75 I setting. Additional downcomer tubes 44 are circulation in the boiler.

preferably also connected between drums 20 and 22 and which are shown as running along the side of the to assist in holding the bafiie in place. Itwill be seen that the major portion of the downpass 34 is free of boiler tubes and we utilize this space in accordance with our invention to increase the efficiency of the down-comers of the boiler. For this purpose we place in the pass 34 a heater 46 whose working temperature is lower than the normal working temperature of the boiler. The heater 46 is preferably either a superheater for reheating steam between two stages of a prime mover or a feedwater heater for heating the water for the boiler. The downcomer tubes of the boiler are so placed as to radiate to the heater 46, thereby oil-setting, at least to a great extent, the tendency otherwise present toward the generation of steam in the downcomers due to absorption of heat from the combustion gases. The downcomers of the boiler therefore are able to operate at maximum efiiciency since the water columns therein contain few if any, steam bubbles and therefore have a maximum density. It will be seen also that all the riser tubes of the boiler are screened from the heater 46 by the bafile 16 so that there is no olfsetting detraction from the natural circulation of the water due to any action of the heater 46 on the risers. Of course, if any of the risers of the boiler were free to radiate to the heater46, the loss of heat from the risers would decrease the percentage of steam in the water contained therein, thereby decreasing the hydraulic head for causing the It will be seen that the presence of tubes 44 between the bafile 16 and heater 46 is not essential as they are not required to protect the riser tubes from radieting heat to the heater 46. However, by

.placing some of the'downcomer tubes on one side and some on the'other side of the heater,

the area of the heater which can receive radiation from the downcomers is increased and the total effect of the heater in promoting the efliciency of the downcomers and circulation of the boiler is also correspondingl increased. It will be clear, moreover, that t e tubes 44 illustrated as adjacent to the baflle 16 may be" distributed among'the two rows of downcomer tubes 38 and 40 if desired, this being the'ordinary practice to allot two rows of tubes to the down circulation in the boiler.

pass 34 adjacent the baffle 16 It w 11 be understood, therefore, that the tubes in rows 38 and 40 are spaced somewhat far er apart than usual in the direction of the axes of drums 20 and 22 and that the tubes thereby omitted from the rows 38 and 40 are placed in the row 44, the percentage of downcomer cross-section in the boiler illustrated being about the average; Owing, however, to the high efficiency of the downcomer space in our boiler due 'to the cooling effect on the downcomers of heat absorbing member 46, the boiler illustrated can be operated at very high rates without injury.

It will be seen that the tubes 12, 16, 44 and 38 form a group which is heated largely by contact with gases from the combustion chamber 10. Owing to the large amount of heat absorbed by tubes 24, 28 and 30, however, the contact or convection heated tubes require not as much floor space as is ordinarily allotted to the combustion chamber. This is especially the case when the convection heated tubes have a greater projection on the vertical than on the horizontal plane, a desir- 9 able arrangement for tubes operating at high ratings.

In accordance with one feature of our invention, these circumstances are turned" to space in addition to that allotted to the combustion chamber 10 and also that the head room required for the convection heated generating tubes is only that needed for tubes expected to operate at high ratings, at least part of the time. As the passes 14 and 34and the tube-free spaces therein in which the superheater and additional heater 46 are located run parallel to drums 20 and 22 from side to side of the boiler, the problem of where to put the reheater or feed-water heater issolved automatically in an installation in accordance with our invention.

What we claim is:

1. The combination with a boiler having a furnace chamber with steam generating tubes on its walls, an up-pass receiving gases from said chamber, a group of generating tubes in said pass over and. between which the gases flow, a down-pass connected to said up-pass, a bafile separating said passes, downcomer tubes in said down-pass in juxta osition to said baflle, connections where y said enerating tubes and said downcomer tubes heater in said down-pass havin a working temperatureless than that of t e boiler.

2. A boiler installation having a combustion chamber provided with water oooled' orm a circulating system of a walls, a group of tubes having a thermal circulation therein arranged directly above said chamber and so as to receive gases of combustion therefrom for heating the tubes, means 1 forming an up-pass and a down-pass within the space outlined by said tubes, said up-pass having a connection tosaid chamber at its lower end and said passes having a connection at their upper ends, said passes having spaces therein free of said tubes running the full horizontal breadths of the passes, said up-pass having a superheater in it tube-free space and said down-pass having an additional heater distinct from said superheater in its own tube-free space.

3. A boiler installation as set forth in claim 2 and in which the additional heater is a feedwater heater.

4. A boiler installation as set forth in claim 2 and in which the additional heater is a steam reheater.

5. The combination with a boiler having a furnace chamber, an up-pass containing generating tubes and receiving gases from said chamber, a down-pass connected to said uppass, a baffle separating said passes, a set of downcomer tubes in said down-pass in juxtaposition to 'said bafile, a second set of downcomer tubes in said down-pass but on the side thereof opposite to said "baffle, connections whereby said generating tubes and said downcomer tubes form a circulating system, of a heater in said down-pass intermediate said sets of tubes and having a working temperature less than that of the boiler.

WILBUR H. ARMACOST. DAGOBERT W. RUDORFF. 

